When a plurality of access points are provided in a wireless Local Area Network (LAN), it is possible to reduce the amount of usage of upper-level communication channels and to realize an improvement in response time to respond to users, by installing a content cache function in each of the access points.
In such an environment where two or more cache-attached access points are positioned in the vicinity of one another, it is possible to efficiently use content by making cached content stored in each of the access points available to the other access point. In that situation, it is necessary to share, among the access points, information about the access points positioned nearby and information about the cached content stored in the access points positioned nearby. When Internet Cache Protocol (ICP) is used, because it is necessary to designate Uniform Resource Locators (URLs) of the content, a huge amount of checking cost is required.
Further, when a piece of content requested by a user has not been cached in an access point, the access point needs to acquire the piece of content from a server, which makes the user's wait longer. Even when the piece of content has been cached in the access point, if the data size of the piece of content is extremely large, it takes a long time to download the piece of content, which in turn makes the user's wait longer.